Determinants of exercise-induced ST-segment displacement in the aVL lead in patients with known or suspected coronary artery disease

Although the aVL lead in exercise electrocardiography is reported to be hel pful in identifying a significant narrowing of the left anterior descending coronary artery (LAD), its role in exercise testing has not been fully eva luated. Accordingly, 821 patients who underwent both standard exercise test ing and coronary angiography were evaluated. In patients with aVL lead ST e levation, the incidence of a significant narrowing of the LAD (124/165 vs 3 48/656; p<0.001) was higher than in those without. Multiple logistic regres sion analysis revealed that the 2 most important variables that correlated with aVL lead ST elevation were a greater number of leads with ST depressio n in the:inferior leads and a smaller amplitude of R wave in the aVL lead. In contrast, variables correlating with aVL lead ST depression in the major ity of cases were, a greater number of leads with ST depression in all lead s and the presence of inferior lead ST elevation. The results of this study indicate that although aVL lead ST elevation could be a marker for LAD nar rowing, more important factors such as inferior lead ST-segment depression and the R-wave amplitude of the aVL lead should; be taken into consideratio n. In contrast, ST depression in the aVL lead mostly represents exercise-in duced myocardial ischemia of greater extent and severity.